Single handed controlled trailer hitch

ABSTRACT

A hitch includes a control linkage having a single handle on a control bar. The control linkage doubles to provide both a positive safety feature and a movement feature to the hitch, permitting single handed operation of both the positive safety feature and the opening of the hitch with the single handle. A release throw of four inches or less opens jaws of the hitch. A latch is included which can secure the control bar in either a secured position or in a release position. A follower is secured to one of the jaws to maintain timing between the jaws, and the follower doubles as a hitch position indicator so an operator to easily visually discern the position of the hitch. By including kingpin recesses of appropriate location and depth on the jaws, the hitch can be used with or without a lube plate over the skid plate.

CROSS-REFERENCE TO RELATED APPLICATION(S)

None.

BACKGROUND OF THE INVENTION

The present invention relates to trailer hitches, and more particularly,to trailer hitches for fifth wheel or gooseneck type trailers supportedsuch as in the bed of a pick-up truck and which are operated bymechanical controls.

Fifth wheel and gooseneck type trailers are used with pick-up trucks tosupport and tow a trailer by placing the weight and load of the trailergenerally over the rear axle of the pick-up truck rather than over oradjacent the rear bumper. Hitches for fifth-wheel and gooseneck trailershave found a large and long-standing acceptance in the marketplace fortowing a wide variety of trailers.

One common type of fifth-wheel trailer includes a kingpin which extendsgenerally vertically on the leading tongue of the trailer. The hitchengages the trailer by surrounding the kingpin. One example of such afifth-wheel hitch is disclosed in U.S. Pat. Nos. 6,846,000 and6,935,650, which includes two movable plates or jaws which engage aroundthe kingpin. The hitch disclosed in U.S. Pat. Nos. 6,846,000 and6,935,650 has a control lever for moving the jaws to release thekingpin. A safety pin provides a positive locking feature which preventsunintended release of the hitch.

An example of a gooseneck hitch is disclosed in U.S. Pat. No. 6,533,308,which includes a pop-up ball rather than kingpin engaging jaws. Thegooseneck hitch disclosed in U.S. Pat. No. 6,533,308 includes araising/lowering linkage with a handle which extends into the rear wheelwell of the pick-up truck, a convenient spot for the operator to controlthe operation of the hitch without climbing into the bed of the pick-uptruck.

The average operator of a fifth-wheel or gooseneck hitch is not young,such as over 55 years old, who is perhaps not as strong and nimble as heor she once was. The controls of the hitch should be readily accessibleby the operator, without requiring too much climbing or bending toaccess. Operation of the controls should not require the application ofexcessive force or torque. The hitch must be strong to securely engagethe trailer, minimizing the possibility of breakage or of any way thetrailer could inadvertently come loose. At the same time, the hitchshould be simple to operate, so the operator has no difficulty inintentionally engaging and disengaging the trailer. The hitch shouldpreferably be mechanically operated, so there is no possibility of aloss of power preventing operation of the hitch. The hitch must berobust and reliable, to last for carefree operation over the life of atleast one vehicle, and possibly over the life of several vehicles,despite the fact that the hitch will likely be openly exposed to weatherover its years or decades of use. As much as possible, the hitch shouldalso have minimal cost and expense in manufacturing and assembly.

BRIEF SUMMARY OF THE INVENTION

The present invention is a hitch, a control linkage for a hitch and amethod of hitch operation. In one aspect, a single handle, with a shortrelease throw, moves a control rod both to provide a safety function andto open the hitch. In another aspect, the control rod translates in asleeve, and a latch is included which can secure the control bar ineither a secured position or in a release position. In another aspect, afollower is secured to one of the jaws to maintain timing between thejaws, and the follower doubles as a hitch position indicator so anoperator to easily visually discern the position of the hitch. Byincluding kingpin recesses of appropriate location and depth on thejaws, the hitch can be used with or without a lube plate over the skidplate. In another aspect, the jaws are mounted with a bearing structurewhich is stiffer in roll than in pitch.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view from above showing a preferred embodimentof a hitch in accordance with the present invention.

FIG. 2 is an exploded perspective view of the hitch of FIG. 1.

FIG. 2 a is an enlarged view of a portion of FIG. 2, showing the bearingcomponents of the preferred embodiment.

FIG. 2 b is an enlarged view of a portion of FIG. 2, showing the controllinkage components of the preferred embodiment.

FIG. 3 is a side view of the preferred base plate.

FIG. 4 is a diagram of the preferred cam ramps of the base plate of FIG.3.

FIGS. 5-10 are simplified plan views of the control linkage components,showing operation of the hitch from a closed, locked position (FIG. 5),in time steps (FIGS. 6 and 7) to a fully open position (FIG. 8), andthen in time steps (FIGS. 9 and 10) before returning to the closed,locked position (FIG. 5).

FIG. 11 is a cross-sectional view of a portion of the preferred hitch inthe closed, locked position, taken along lines 11-11 of FIG. 5.

FIG. 12 is a cross-sectional view of the same portion of the preferredhitch in the fully open position, taken along lines 12-12 of FIG. 8.

FIG. 13 is a simplified cross-sectional elevational view of the hitchabout a kingpin, showing the release position of the controlled jaw indashed lines.

FIG. 14 is a simplified cross-sectional elevational view of the hitchabout a kingpin with a lube plate over the skid plate, showing therelease position of the controlled jaw in dashed lines.

While the above-identified drawing figures set forth one or morepreferred embodiments, other embodiments of the present invention arealso contemplated, some of which are noted in the discussion. In allcases, this disclosure presents the illustrated embodiments of thepresent invention by way of representation and not limitation. Numerousother minor modifications and embodiments can be devised by thoseskilled in the art which fall within the scope and spirit of theprinciples of this invention.

DETAILED DESCRIPTION

As shown in FIGS. 1 and 2, a preferred embodiment of a hitch 20 inaccordance with the present invention includes a support frame 22 whichpermits attachment of the hitch 20 into the bed of a pick-up truck (notshown). A skid plate 24 provides the top surface of the hitch 20 anddefines a king-pin receiving slot 26. The skid plate 24 may embody anornamental design such as described in U.S. Patent Application No.C475.12-11, assigned to the assignee of the present invention andincorporated by reference. Two jaws 28, 30 are positioned under the skidplate 24 and are used as a kingpin retention structure to engage thekingpin 32 (shown in FIGS. 13 and 14) of a towed vehicle (not shown).The jaws 28, 30 are rotationally attached each on a hub 34. One of thejaws is a controlled jaw 28, moveable in the height direction on its hub34, while the other jaw is a fixed height jaw 30. A linkage 36 controlsoperation of the jaws 28, 30, with the linkage 36 being operable via ahandle 38. The jaws 28, 30 are supported by and protected in a jawhousing 40, which in turn is supported by the support frame 22. The jawhousing 40 has a kingpin opening 42 on its aft wall.

As better shown in FIG. 2, the preferred support frame 22 generallyincludes legs 44 and a bearing structure 46, with the bearing structure46 supported by a bearing undercarriage 48. The preferred legs 44 areprovided as identical right and left side legs, and provide anappearance of right to left and front to back symmetry to the hitch 20.The bearing undercarriage 48 mounts between the right and left side legs44. For instance, the legs 44 may embody the ornamental design describedin U.S. Patent Application No. C475.12-12, assigned to the assignee ofthe present invention and incorporated by reference. If desired, theframe 22 may permit fore and aft, height, and side-to-side flexibilityin mounting position. A basic frame structure is disclose in U.S. Pat.Nos. 6,846,000 and 6,935,650 to Grinde et al., owned by the assignee ofthe present invention and incorporated herein by reference. The presentinvention is disclosed and explained as an improvement of the hitch andframe structure of U.S. Pat. Nos. 6,846,000 and 6,935,650, but thevarious aspects of the invention can be used with a wide variety ofother hitch and frame structures.

The preferred bearing structure is a shaft-supported spherical bearing46 to permit angular movement in all directions (other than elevation)of the skid plate 24 and jaws 28, 30, enabling the hitch 20 to permitangled pitch and roll movement of the kingpin 32 as the vehicletraverses over hills, across side slopes, around corners, etc., when thetrailer rides on an undulating roadplane behind the towing vehicle. Thebearing undercarriage 48 supports the bearing shaft 46 at severallocations along its length.

The bottom of the jaw housing 40 is provided by a base plate 50 as shownin FIGS. 2, 2 a and 3. A peripheral side wall 52 fixedly attaches to thebase plate 50 such as through a bolted or welded connection. The bearingstructure 46 preferably biases the jaw housing 40 toward an alignedposition, wherein the jaw housing 40 (and the jaws 28, 30 mountedtherein) are in a plane parallel to a bottom attachment plane defined bythe legs 44 of the frame 22, i.e., parallel to the plane of the bed ofthe truck into which the hitch 20 is attached.

In the preferred embodiment, the base plate 50 includes three extensionbars 54, 56, 58 for alignment biasing: a central extension bar 54, afore extension bar 56 and an aft extension bar 58. The extension bars54, 56, 58 all preferably extend radially relative to the center of thespherical bearing 46. In the preferred configuration, the extension bars56, 54, 58 are one behind the other, in a fore-aft plane perpendicularto the base plate 50 (i.e., a generally vertical fore-aft plane).

A bottom elastomeric pad 60 is provided which mates around the centralextension bar 54, biasing the central extension bar 54 back toward analigned position. The bottom elastomeric pad 60 is retained in a bottompad housing 62, which attaches to the bearing undercarriage 48 and keepsthe bottom elastomeric pad 60 in a generally constant position relativeto the bearing undercarriage 48. When the jaw housing 40 is not in thealigned position, the central extension bar 54 causes compression of thebottom elastomeric pad 60 in the direction that the central extensionbar 54 is out of alignment. The bottom elastomeric pad 60 respondsagainst the compression force, biasing the central extension bar 54horizontally, in a radial direction relative to the longitudinal axis ofthe central extension bar 54, back toward the aligned vertical position,in the exact radial direction needed for alignment.

A fore elastomeric pad 64 mates around the fore extension bar 56, and anaft elastomeric pad 66 mates around the aft extension bar 58. The foreand aft elastomeric pads 64, 66 are received between two cross-members68 of the bearing undercarriage 48. The fore and aft elastomeric pads64, 66 have a width which matches the width of the opening between thetwo cross-members 68. However, in contrast to the bottom elastomeric pad60 as constrained by the bottom pad housing 62, the cross-members 68permit the fore and aft elastomeric pads 64, 66 to slide in the fore andaft directions.

The bottom elastomeric pad 60 provides an alignment biasing force whichis generally consistent both in pitch and in roll of the towed trailerrelative to the towing vehicle. For instance, a 2° roll offset of thebase plate 50 creates an alignment force in the bottom elastomeric pad60 of the same magnitude as a 2° pitch offset of the base plate 50,though the 2° roll offset creates a sideways force while the 2° pitchoffset creates a fore-aft force. All 2° offsets which are combinationsof pitch and roll will also provide a compression force in the bottomelastomeric pad 60 of the same general magnitude, just in the properdirection for alignment.

In contrast to the relatively equal pitch and roll forces provide by thebottom elastomeric pad 60, the fore and aft elastomeric pads 64, 66provide essentially no pitch alignment force. When the towing vehicletraverses over hills and valleys with no side slope, the hitch 20 willallow pitch offset in which the fore and aft elastomeric pads 64, 66will not compress but will merely slide fore and aft between thecross-members 68. When the towed trailer rolls relative to the towingvehicle, the roll will cause the fore and aft elastomeric pads 64, 66 tocompress and providing a horizontally sideways correction force. Thus,the fore and aft elastomeric pads 64, 66 cause the hitch 20 to bestiffer against roll than against pitch. The higher roll stiffness isillustrated in FIG. 3 by the arrows, wherein the larger arrows 70indicate the compressive force which can be provided by the elastomericpads 60, 64, 66 and the lined arrows 72 represent the translation in thepitch direction without compression permitted by the fore and aftelastomeric pads 64, 66. The amount of roll stiffness and the amount ofpitch stiffness can be easily selected by a worker skilled in the art byappropriately sizing the bottom elastomeric pad 60 relative to the foreand aft elastomeric pads 64, 66, and by selecting the moment arm of eachof the elastomeric pads 60, 64, 66 on their respective extension bars54, 56, 58.

The shape of the bottom elastomeric pad 60, the opening 74 of the bottomelastomeric pad 60 for receiving the central extension bar 54, and thecross-sectional shape of the central extension bar 54 are preferably allsquare just for ease of manufacturing and assembly. The shape of thefore and aft elastomeric pads 64, 66, the openings 76 of the fore andaft elastomeric pads 64, 66 for receiving the fore and aft extensionbars 56, 58, and the cross-sectional shape of the fore and aft extensionbars 56, 58 are preferably all square just for ease of manufacturing andassembly. The hitch 20, including the bottom and fore and aftelastomeric pads 60, 64, 66, does not provide a significant alignmentforce in the yaw direction, as the kingpin 32 is cylindrical andtransmits essentially no yaw force to the jaws 28, 30.

As one alternative to elastomeric pads 60, 64, 66, the alignment forcefor the bearing structure 46 could be provided by other biasing members,such as springs. Elastomeric pads work well for the alignment forcebecause they can provide the compression force in all directions, whichever direction is needed to make the correction into alignment.

As better shown in FIGS. 2 b and 6-12, the jaws 28, 30 are operated by acontrol rod 78 through the linkage 36. The handle 38 is at the proximalend of the control rod 78, bent at an angle relative to the longitudinalaxis of the control rod 78. With the handle 38, an operator can easilyapply a translational motion pulling or pushing the control rod 78 alongits longitudinal axis. The control rod 78 generally translates between aclosed position, wherein the control rod 78 extends over the controlledjaw 28, and a release position wherein the control rod 78 is pulled backoff the surface of the controlled jaw 28.

The control rod 78 extends through a slotted sleeve 80. The slottedsleeve 80 provides support for the control rod 78, maintaining thecontrol rod 78 on its longitudinal axis. The slotted sleeve 80 can bedirectly supported by the frame 22, but more preferably is rigidlyattached to the jaw housing 40 to move with the jaws 28, 30 and jawhousing 40 on the bearing structure 46. A slot 82 on the slotted sleeve80 allows an attachment link 84 to extend through the slotted sleeve 80and connect to the control rod 78.

A spiral lift cam 86 is positioned on the hub 34 underneath thecontrolled jaw 28. The spiral lift cam 86 operates essentially asdisclosed in U.S. Pat. Nos. 6,846,000 and 6,935,650. The base plate 50includes a mating opening 88 for the spiral lift cam 86. The matingopening 88 has one or more ramps 90, which cooperate with ramps 92 onthe bottom of the spiral lift cam 86. The preferred profile for theramps 90 is shown in FIG. 4, which shows two opposing ramps operatingover a throw of about 78°, and then has a 25° landing dwell.

As best shown in FIGS. 2 b, 11 and 12, a compression spring 94 biasesthe controlled jaw 28 and the underlying spiral lift cam 86 downward.When the spiral lift cam 86 is pivoted about the hub 34, the ramps 92 onthe bottom of the spiral lift cam 86 ride up the ramps 90 on the matingopening 88, raising the spiral lift cam 86 and the controlled jaw 28above it against the compression spring 94.

The preferred attachment link 84 includes an attachment pin 96 and anattachment bar 98. The attachment pin 96 extends through the control bar78 and resides in the slots 82 of the slotted sleeve 80. The attachmentbar 98 pivotally connects the attachment pin 96 to the spiral lift cam86. A distal end of the attachment pin 96 is connected to a tensionspring 100. The tension spring 100 extends through a tension springwindow 102 in the jaw housing wall 52, and the opposite end of thetension spring 100 biases off a tension spring mount 104 fixed on thejaw housing 40. The attachment bar 98 extends through an attachment barwindow 106 on the jaw housing 40. The size of the attachment bar window106 should permit side-to-side angular movement of the attachment bar 98and the spiral lift cam 86 as the control linkage 36 moves between theclosed and release positions. The size of the attachment bar window 106should also permit some angular up-and-down movement of the attachmentbar 98 as the spiral lift cam 86 rises or lowers relative to the fixedheight of the slotted sleeve 80. When the control bar 78 is pulled orpushed within the slotted sleeve 80, the attachment pin 96 translateswith the control bar 78. The attachment bar 98 then torques the spirallift cam 86 about the movable jaw hub 34. The tension spring 100 biasesthe control bar 78 toward the closed position, with the spiral lift cam86 nesting downward in the mating opening 88.

A latch 108 permits the control bar 78 to be secured at either theclosed position or at the release position. The preferred latch 108 ishinged relative to the slotted sleeve 80 with a hinge pin 110, andincludes an interference flat 112 which mates with either a closed latchrecess 114 or a release latch recess 116 on the control bar 78. Thelatch 108 can then be held downward into an interference position,mating with either the closed latch recess 114 or the release latchrecess 116, with a safety pin 118. With the latch 108 in theinterference position, the latch 108 prevents translation of the controlbar 78. If desired, the latch 108 may be either biased open or biasedclosed such as with a spring (not shown), which would minimize rattlingof the latch 108 in the interference position during towing and affecthow the latch 108 moves into and out of the interference position.However, the preferred embodiment allows the latch 108 to freely rotateabout the hinge pin 110 under only gravitational forces, which lightlybias the latch 108 either toward the interference position or toward anopen position depending upon where the latch 108 is released in itshinged arc.

The fixed height jaw 30 is preferably biased toward an open position. Inthe preferred embodiment, a torsion spring 120 is mounted about thefixed height hub 34, providing a biasing force from a torsion springmount 122 fixed on the jaw housing 40 to a side of the fixed height jaw30.

A follower 124 is mounted on the fixed height jaw 30 in a configurationfor cooperating with the controlled jaw 28. The preferred follower 124is formed from bent bar stock which is welded or otherwise fixedlysecured to the fixed height jaw 30. The follower 124 causes thecontrolled jaw 28 to open with the opening of the fixed height jaw 30. Astop 126 is provided which stops the controlled jaw 28 from rotatingpast the closed position. The follower 124 and the stop 126 togetherensure that the two jaws 28, 30 do not get “out-of-time” wherein one jawin the open position nests in the other jaw in the closed position.

A viewing opening 128 in the fore side of the jaw housing 40 permitsoperator viewing of the follower 124 from the cab of the vehicle. Theslots 82 in the slotted sleeve 80 permit operator viewing of markedportions of the control rod 78. For instance, green dots may be paintedon the control rod 78 and on the follower 124 which are only visiblewhen the fixed height jaw 30 is rotated back into the closed positionand when the control rod 78 is in the closed position indicating thatthe controlled jaw 28 is positioned downward beneath the distal end ofthe control rod 78. In its preferred configuration, the positionindicator dot(s) is/are viewable from the forward side of the hitch 20,so the operator can check the position indicator from the cab of thepick-up truck prior to driving with the towed vehicle, thereby ensuringthat the kingpin 32 is locked in the hitch 20. The operator should onlydrive with a towed vehicle after checking to make sure the positionindicator is “green” signifying that the hitch 20 is locked closed. Ayellow dot may be painted on the control rod 78 which is visible throughthe sleeve 80 only when the control rod 78 is in an intermediateposition indicating that the controlled jaw 28 is ready to receive thekingpin 32. A red dot may be painted on the control rod 78 which isvisible only when the controlled jaw 28 is fully opened into the releaseposition, signifying that the hitch 20 will not lock about a kingpin 32but rather is uncoupled from the kingpin 32.

Operation of the hitch 20 is explained with reference to FIGS. 5-12. Asshown in FIG. 5, the hitch 20 is depicted as beginning in a closed,locked position. The controlled jaw 28 is biased downward by thecompression spring 94. The controlled jaw 28 is further positively helddownward by the control bar 78 extending over the top surface of the jaw28. With the controlled jaw 28 in its downward position, it mates withthe fixed height jaw 30 and cannot pivot or open. With the control bar78 in place positively securing the controlled jaw 28 down, there is nopossibility of the controlled jaw 28 rising up out of plane with thefixed height jaw 30 to an unsecured position. The control bar 78 isbiased by the tension spring 100 to an extended position (to the rightin FIG. 5). The follower/position indicator 124 is in its forwardposition, visible to an operator in the cab of the vehicle to signifythat the jaws 28, 30 are closed and secured. The latch 108 is closedinto an interference position, and held closed by the safety pin 118.

When the operator of the hitch 20 wants to release the trailer from thehitch 20, first the safety pin 118 is pulled, and the latch 108 isopened. Then the control handle 38 is pulled as shown by arrow A in FIG.6. The operator must pull sufficiently hard to overcome the biasingforce of the tension spring 100, but the handle 38 extends at a rightangle to the pull direction, making it easy for an operator transmit asignificant pull force to intentionally overcome the spring bias whendesired. As the control handle 38 begins to move, the attachment bar 98pulls the spiral lift cam 86 and the spiral lift cam 86 begins to rotateabout the hub 34. The spiral lift cam 86 rotates towards the landingdwell without lifting, until the control bar 78 has been retracted(translated) beyond the top surface of the controlled jaw 28.

Once the control bar 78 clears the top surface of the controlled jaw 28,the ramps 92 on the spiral lift cam 86 ride up the ramps 90 in the baseplate 50, lifting the spiral lift cam 86 and the controlled jaw 28against the compression spring 94. The pull force must now overcome thecombined force of both the tension spring 100 and the compression spring94 (through the ramp angle), as well as the gravitational force on thecontrolled jaw 28 and the spiral lift cam 86. However, the tensionspring 100 and the compression spring 94 need not have high springconstants, so a pull force on the order of 5 to 25 pounds can open thehitch 20. FIG. 6 shows the hitch 20 during the opening motion just afterthe spiral lift cam 86 has begun rising. At this point, if the operatorreleases pull on the handle 38 without completing a full release stroke,the hitch 20 will react to the forces of the tension spring 100 and thecompression spring 94 and return to the closed position of FIG. 5.

If the operator continues pulling on the handle 38, the control linkage36 will continue to pull the spiral lift cam 86 clockwise (as shown inFIG. 7) which continues to raise the controlled jaw 28 to an elevationwhere it clears the fixed height jaw 30. The total release of the hitch20 is achieved in a handle throw of only about 3 to 6 inches andpreferably a complete handle throw of 4 inches or less.

Once the controlled jaw 28 clears the fixed height jaw 30, the torsionspring 120 on the fixed height jaw 30 biases the fixed height jaw 30open, pivoting counterclockwise about the fixed height hub 34. Due tothis rotation, the follower 124 contacts the controlled jaw 28 in theposition shown in FIG. 7. The stop 126 is most important at this time,as it prevents the controlled jaw 28 from the possibility of pivotingcounterclockwise into an out-of-time position with respect to the fixedheight jaw 30. Additionally, friction between the spiral lift cam 86 andthe controlled jaw 28 creates the tendency for the controlled jaw 28 topivot in the same direction as the spiral lift cam 86, clockwise. Withthe controlled jaw 28 prevented from counterclockwise rotation due tothe stop 126 and started in the clockwise direction due to friction withthe spiral lift cam 86, the follower 124 readily continues the openingof the controlled jaw 28 under the force of the torsion spring 120. Thehitch 20 opens and tends to “eject” the formerly held kingpin 32, so thehitch 20 can be driven away from the towed vehicle and its kingpin 32.

If desired, the hitch 20 may be secured in this fully open position byclosing the latch 108 and securing the latch 108 with the safety pin118. In many instances, the weight of the trailer and the frictionalreluctance of the trailer to move (for a “heavy load”) will be greaterthan the opening force provided by the torsion spring 120. That is, thehitch 20 will not eject a heavy load upon reaching the release position.In such cases, merely raising the controlled jaw 28 to the releaseposition will not by itself open the hitch 20, and releasing of the pullforce on the handle 38 prior to closing the latch 108 into the releaserecess 116 will cause the hitch 20 to revert back to the closed positionof FIG. 5 under the force of the tension spring 100 and the compressionspring 94. With the hitch 20 held in the fully open position, the spirallift cam 86 holds the controlled jaw 28 up and out-of-plane with thefixed height jaw 30, and the jaws 28, 30 will not unintentionallyreclose around a kingpin 32. With a heavy load, the operator may use the“held open” position to drive the towing truck out from under thekingpin 32 of the heavy load, causing the hitch 20 to spring open to theposition of FIG. 8. If desired, the operator may also take advantage ofthe “held open” hitch position during reattachment of the towed kingpin32 to the hitch 20, i.e., while positioning the trailer and kingpin 32to the general vicinity desired relative to the hitch 20. So long as thehitch 20 is in the “held open” position of FIGS. 8 and 12 (either due toforce on the handle 30 or to the latch 108 engaging the release recess116), there is no possibility of the controlled jaw 28 moving downwardinto a locked position.

Once the kingpin 32 is no longer in the hitch 20, the torsion spring 120fully opens the jaws 28, 30 to the release position shown in FIGS. 8 and12. Once the fixed height jaw 30 is open, the rear corner of the fixedheight jaw 30 prevents the controlled jaw 28 from moving back downwarddespite the biasing force of the compression spring 94. Typically aftersome time has passed after releasing the kingpin/trailer, the operatormay desire to use the hitch 20 again. Opening of the latch 108 out ofthe release recess 116 (or releasing pull on the handle 38 without everclosing the latch 108) causes the handle 38 to translate back toward thecontrolled jaw 28 to the “load” position shown in FIG. 9. The force ofthe tension spring 100 moves the control bar 78 until the distal end ofthe control bar 78 contacts the controlled jaw 28. The spiral lift cam86 has lowered back down relative to the base plate 50, but thecontrolled jaw 28 is still held at an elevated position due to theunderlying fixed height jaw 30. The force of the torsion spring 120keeps the jaws 28, 30 open even though the tension spring 100 and thecompression spring 94 are biasing the controlled jaw 28 toward a closedposition. However, this force balance is readily overcome when a kingpin32 is pressed into the hitch 20. The kingpin 32 (shown in FIGS. 13 and14) provides a pushing force K which is used to push the jaws 28, 30backward until they close around the kingpin 32, to the position shownin FIG. 10. Once the jaws 28, 30 are aligned about the kingpin 32, thecontrolled jaw 28 clears the fixed height jaw 30, and the compressionspring 94 forces the controlled jaw 28 downward into the plane of thefixed height jaw 30 and into engagement with the fixed height jaw 30.Once the controlled jaw 28 moves downward under the force of thecompression spring 94, the control rod 78 is free to complete itsmovement over the controlled jaw 28 to the position shown in FIGS. 5 and11. With the controlled jaw 28 in the “down” position, thefollower/position indicator 124 is again visible through the view windowto an operator in the cab of the pickup truck. Once the kingpin 32 is inplace and engaged within the jaws 28, 30, the operator can close thelatch 108, again creating positive interference between the latch 108and the control rod 78 to prevent the control rod 78 from unintendedmovement.

As best shown in FIGS. 13 and 14, the vertical dimensions of the hitch20 as it engages the kingpin 32 are quite important to ensure that thehitch 20 and jaws 28, 30 are appropriately strong to support the load ofthe kingpin 32 during towing. For instance, an upward force on thekingpin 32 will transmit to the jaws 28, 30 and then from each jaw 28,to its hub 34 as a bending moment. To support bending moments at theconnection between the jaws 28, 30 and the hubs 34, each of the jaws 28,30 have a collar 130, 132 around its hub 34 (and inside the respectivesprings 94, 120) that, in the preferred embodiment has an insidediameter of about 25 mm and a height of at least about 27 mm. The twojaws 28, 30 mate to form a circular central opening for receiving a 50.8mm (2 inch) diameter neck 134 on the standard kingpin 32. To transmitthe towing force from the hubs 34 to the jaws 28, 30, the jaws 28, 30are formed of 1045 steel and have a preferred height or thickness t of16 mm. The spiral cam ramps 90, 92 have a lift height of cam action 1which raises the controlled jaw 28 18 mm so the controlled jaw 28 willreadily clear the fixed height jaw 30 upon opening. While the neck 134of standard kingpins has a 36.5 mm height which will permit the full 34mm range of contact (16 mm thickness plus 18 mm height change) of thecontrolled jaw 28, placement of the kingpin 32 at different heightsrelative to the hitch 20 can upset the mating relationship in heightbetween the jaws 28, 30 and the kingpin 32. For instance, one commonapplication is to insert a lube plate 136 around the kingpin 32 so thelube plate 136 rides on the skid plate 24, reducing or minimizing theneed to grease the skid plate 24. The lube plate 136 may be formed of astrong bearing material, at a thickness of no more than 3/16 of an inch.The additional height of the lube plate 136 raises the kingpin 32relative to the jaws 28, 30.

To account for the potential variance in height of the kingpin 32relative to the jaws 28, 30, the jaws 28, 30 have kingpin receivingrecesses 138, 140 defined therein. On the bottom side of the fixedheight jaw 30 and the bottom side of the controlled jaw 28, a kingpinreceiving recess 138 is defined, shaped to mate with the kingpin 32 uponentry and removal of the kingpin 32 from the hitch 20. The preferredbottom side kingpin receiving recesses 138 are 2 mm deep. On the topside of the controlled jaw 28, a topside kingpin receiving recess 140 isdefined, shaped to mate with the kingpin 32 upon entry and remove of thekingpin 32 from the hitch 20. The preferred top side kingpin receivingrecess 140 is about 5 mm deep. With the bottom side and top sidereceiving recesses 138, 140, the contact area of the controlled jaw 28on the kingpin 32 has a contact height h on the kingpin 32 which is nogreater than 10 mm, such as about 8.75 mm. Even when this controlled jaw28 is raised 18 mm (to the height shown by dashed lines 28 a) to clearthe height of the fixed height jaw 30, the full range of contact of thecontrolled jaw 28 on the kingpin 32 is 28 mm or less, allowing use of alube plate 136 of up to about 3/16 inch (4.5 mm). By having the narrowcontact height, the kingpin 32 can be secured within the jaws 28, 30 atdifferent heights relative to the hitch 20 depending upon whether a lubeplate 136 is or is not present

In considering the operation of the preferred embodiment, the numerousadvantages of the present invention become apparent. One significantadvantage is that the invention in one aspect permits single-handedmanipulation of a single control (handle 38) to provide both the safetyfunction and the hitch movement function. The handle 38 is moved througha first range of travel throughout which it positively secures thecontrolled jaw 28 at the closed position. Until the handle 38 is pulleda sufficient distance that the control bar 78 no longer overlies andcontacts the top side of the controlled jaw 28, there is no possibilityof the controlled jaw 28 moving upward and no possibility of inadvertentrelease of the hitch 20. The same handle 38 is then moved through asecond range of travel throughout which it lifts the controlled jaw 28to the release position. The operator can readily open the hitch 20using a single hand, by undoing the latch 108 and with a simple movementof the handle 38.

A second advantage involves the fact that opening of the hitch 20involves translation (pulling and/or pushing) of the handle 38 ratherthan pivoting or torqueing of the handle 38. Operators are able toimpart greater forces in pulling and/or pushing a handle 38 than theycan impart in turning or twisting of the handle 38. Even if the operatordoes not have great hand strength, the forces of the tension spring 100and the compression spring 94 can be overcome by imparting translationalforces on the handle 38.

A related advantage results from the orientation of forces. Operation ofthe hitch 20 involves raising and lowering the controlled jaw 28.However, it is difficult for many operators to impart a strong raisingforce without standing over the handle 38 to be raised or straining theoperator's back. The preferred embodiment does not require the operatorto impart any vertical force, but rather converts the operator'shorizontal force on the handle 38 to a vertical force on the controlledjaw 28. The horizontal forces imparted by the operator are in push andpull directions relative to where the operator usually stands beside thehitch 20 during operation of the hitch 20, enabling the operator toreadily lean into the direction of push or pull and thereby more easilyimpart a greater force.

Another force orientation benefit is achieved in the interaction betweenthe spiral lift cam 86 and the controlled jaw 28. Namely, frictionbetween the spiral lift cam 86 and the controlled jaw 28 tends to pivotthe controlled jaw 28 in the same direction (clockwise orcounterclockwise) that the spiral lift cam 86 pivots. The spiral liftcam 86 and the controlled jaw 28 both open by clockwise motion and bothclose by counterclockwise motion. By having the spiral lift cam 86 andthe controlled jaw 28 moving in the same direction, the frictionalforces help to open and close the controlled jaw 28 as desired, whichhelps minimize the possibility that the controlled jaw 28 might become“out-of-time” with the fixed height jaw 30, i.e., helps avoid thesituation wherein one jaw in the open position interlocks with the otherjaw in the closed position.

Another related advantage results from the short stroke or throw lengthof the handle 38 of the present invention in opening the hitch 20. Thetotal release of the hitch 20 is achieved in a handle throw of onlyabout 3 to 6 inches and preferably a complete handle throw of 4 inchesor less. The small handle throw necessary to move the hitch 20 from theclosed position to the release position is important when one considersthe small confines of the bed of the pick-up truck in which the hitch 20is installed. With a small throw of four inches or less, the hitch 20can be release by most operators without needing to climb into the bedof the pick-up truck. Even though the handle 38 is pulled outward on theside of the hitch 20, the short throw length enables the hitch 20 to bemounted into beds of all standard sizes, with the kingpin opening 42centrally mounted relative to the bed, and still provide sufficientclearance between the handle 38 and the box of the pickup truckthroughout the handle throw.

The torsion spring 120 in the preferred embodiment provides anotheradvantage. The torsion spring 120 biases the kingpin retention structureprovided by the jaws 28, 30 open when the controlled jaw 28 is raised tothe release position. Accordingly, in light load or no load situations,the hitch 20 “springs” open once the release position of the handle 38is reached. It is very clear to the operator when the handle 38 has beenpulled far enough to release the hitch 20. After the hitch 20 has“sprung” open, it will not close again until after both the handle 38 isreleased back to the load position and the spring force of the torsionspring 120 is overcome by moving the kingpin 32 forward in the kingpinreceiving slot 26.

Another separate advantage of the preferred embodiment involves thefollower/position indicator 124. The operator can readily check to seewhen the hitch 20 is in the closed, secured position. The positionindicator 124 is viewable from the cab of the pick-up truck, so theoperator can look over his or her shoulder and check the positionindicator as needed, such as immediately after driving over a bump inthe road.

Another advantage of the preferred embodiment involves the sleevearrangement for the control rod 78. The sleeve 80 strengthens thecontrol rod 78 against bending or misalignment. The additional stabilityand strength that the sleeve 80 provides to the control rod 78 areparticularly important in cases when the control rod 78 is inadvertentlystepped on or otherwise contacted at an angle to its longitudinaldirection of motion.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. As just one example, the single handedoperation of present invention can be readily applied to a wide varietyof hitch structures.

1. A trailer hitch for engaging a kingpin of a trailer, the trailerhitch comprising: a support frame; a kingpin retention structuresupported by the support frame, the kingpin retention structure in asecured position being securable about the kingpin; an actuationstructure supported by the support frame, the actuation structure beinglinked to the kingpin retention structure for moving the kingpinretention structure from the secured position to a release positionwherein the kingpin can be removed from the kingpin retention structure;and a spring biasing the kingpin retention structure open when in therelease position.
 2. The trailer hitch of claim 1, wherein the kingpinretention structure comprises a first mating jaw and a second matingjaw, and wherein the spring biases at least one of the mating jaws open.3. The trailer hitch of claim 2, wherein the first and second matingjaws interfere with each other when mating in the secured position, suchthat the first mating jaw while in the secured position prevents thesecond mating jaw from opening under the force of the spring, with thespring moving the jaws open after the interference between the first andsecond mating jaws is cleared.
 4. The trailer hitch of claim 3, whereinthe first mating jaw is a controlled jaw and the second mating jaw is afixed elevation jaw, and wherein the interference between the first andsecond mating jaws is cleared by changing the elevation of thecontrolled jaw relative to the fixed elevation jaw.
 5. The trailer hitchof claim 2, wherein the spring is used to move both the first mating jawand the second mating jaw open from the secured position.
 6. The trailerhitch of claim 5, wherein the spring is a torsion spring to pivot thefirst mating jaw open, and wherein a follower is attached to the firstmating jaw which contacts the second mating jaw during opening of thefirst mating jaw, such that the follower pushes the second mating jawopen.
 7. The trailer hitch of claim 6, wherein a window is defined inthe hitch to permit viewing of the follower when the hitch is in thesecured position.
 8. A trailer hitch for engaging a kingpin of atrailer, the trailer hitch comprising: a support frame; a kingpinretention structure supported by the support frame, the kingpinretention structure in a secured position being securable about thekingpin; an actuation structure supported by the support frame, theactuation structure being linked to the kingpin retention structure formoving the kingpin retention structure from the secured position to arelease position wherein the kingpin can be removed from the kingpinretention structure, the actuation structure comprising a handle with areleasing throw length of four inches or less.
 9. The trailer hitch ofclaim 8, wherein the releasing throw of the handle is a translationalmotion in a direction toward or away from a center of the kingpinretention structure.
 10. The trailer hitch of claim 9, wherein handle isconnected to a control rod which translates longitudinally in a sleeve.11. The trailer hitch of claim 9, wherein the handle is connected to acontrol rod which translates longitudinally toward and away from thecenter of the kingpin retention structure, wherein the control rod in aclosed position and in a first part of the releasing throw interfereswith the kingpin retention structure to prevent the kingpin retentionstructure from opening.
 12. The trailer hitch of claim 11, wherein thecontrol rod in a second part of the releasing throw opens the kingpinretention structure to release the kingpin.
 13. The trailer hitch ofclaim 8, wherein the kingpin retention structure comprises a jawcontacting the kingpin in the closed position, and wherein the releasingthrow of the handle operates through a linkage to open the jaw, withfrictional interaction between the linkage and the jaw during thereleasing throw tending to bias the jaw toward the open position.
 14. Atrailer hitch for engaging a kingpin of a trailer, the trailer hitchcomprising: a support frame; a kingpin retention structure supported bythe support frame, the kingpin retention structure in a secured positionbeing securable about the kingpin, the kingpin retention structurehaving a first moveable portion moving in a first movement path and asecond moveable portion moving in a different, second movement path; acontact structure attached to at least one of the first and secondmoveable portions which maintains timing of motion between the firstmoveable portion and the second moveable portion.
 15. The trailer hitchof claim 14, wherein the first moveable portion is a first jaw whichcontacts the kingpin, and wherein the second moveable portion is asecond jaw which contacts the kingpin, and wherein the contact structureis a follower attached to the first jaw which contacts and causes thesecond jaw to move upon movement of the first jaw.
 16. The trailer hitchof claim 14, further comprising a window defined in the hitch forviewing of the contact structure so an operator in the cab of a towingvehicle can determine position of at least one of the first and secondmoveable portions.
 17. The trailer hitch of claim 14, wherein the firstmoveable portion pivots about a first pivot axis, wherein the secondmoveable portion pivots about a second pivot axis, and wherein thecontact structure causes the second moveable portion to pivot in acounter-clockwise direction when the first moveable portion pivots in aclockwise direction.
 18. A trailer hitch for a towing vehicle, thetrailer hitch comprising: a support frame mountable relative to thetowing vehicle; a towing link supported on the support frame, the towinglink being moveable between a first position wherein the hitch ispositioned for towing engagement and a second position wherein the hitchis not positioned for towing engagement; and a control lever coupled tothe towing link, the control lever having a first range of travel forperforming a first, safety function of preventing movement of the towinglink between the first position and the second position and having asecond range of travel for performing a second, movement function ofmoving the towing link between the first position and the secondposition, wherein the control lever is operational with a single hand.19. The trailer hitch of claim 18, further comprising a handle coupledto the control lever, with a total throw length of the handle to movethe control level and the towing link from the towing engagementposition to release is no greater than four inches.
 20. The trailerhitch of claim 18, wherein the towing link comprises a first jaw and asecond jaw each moveable on different travel paths during change fromthe towing engagement position to release.